The designer, who turned a casual clothing line fueled by embroidered tunics and ballet flats with the double T logo into a fashion behemoth, has introduced a new collection of activewear called Tory Sport that's available only online and at a pop-up shop located on a trendy shopping street in Manhattan's Nolita district.

Burch, who was captain of her high school tennis team and still enjoys the sport, spent three years creating the distinctive collection of running, tennis, swimming, exercise studio and "coming and going" clothing that can be worn from working out to lunch or while running errands.

"I started thinking of the elegance of sports and how elegant athletes are and just this idea of marrying real function and style — and the shift in the way that women are dressing," Burch told CultureMap at the pop-up shop during New York Fashion Week.

"I don't love the term 'athleisure,' so we're calling it 'coming and going.' And there's also serious performance wear; but it's not part of the design, it's just a given. I can go on and on. I've learned a lot about fabrics."

The collection, which also includes bags, shoes and accessories, is inspired by classic silhouettes from the '70s, with pleated tennis skirts, anoraks, fitted leggings, oversized sweaters, classic track suits, swimsuits and stylish neoprene coats and skirts. High tech quick-drying fabrics come in old-school stripes and florals. The pop-up shop even sells a classic T-shirt from the era that can be monogrammed in block initials.

"I was inspired by the movie The Royal Tennebaums so I started with that," Burch explained. "But, really, about everything I love is from high school and college. So I wanted to be a bit retro '70s but modern. I'm a big fan of Bjorn Borg, John McEnroe, Jimmy Connors — that era of tennis. But then just athletes in general. We did surfing with neoprene outfits, but I also love the track suits. I feel like they're beautiful enough to wear to lunch or dinner or the airport."

Prices range from $55 for performance tops to $550 for outerwear. Tory Sport is a distinct brand from Tory Burch with its own logo, digital commerce site, packaging and social channels — and Burch said she doesn't plan to expand the brand quickly.

The pop-up store, which is located on the site where the original Tory Burch boutique debuted 11 years ago, will remain open until a permanent store opens in New York's Flatiron District in March.

"And then we'll see," Burch said. "We'll move it to different places, possibly a pop-up in Texas. But nothing definitive. I really want to keep it focused and small."